sgetri (l)  Linux Man Pages
sgetri: computes the inverse of a matrix using the LU factorization computed by SGETRF
Command to display sgetri
manual in Linux: $ man l sgetri
NAME
SGETRI  computes the inverse of a matrix using the LU factorization computed by SGETRF
SYNOPSIS
 SUBROUTINE SGETRI(

N, A, LDA, IPIV, WORK, LWORK, INFO )

INTEGER
INFO, LDA, LWORK, N

INTEGER
IPIV( * )

REAL
A( LDA, * ), WORK( * )
PURPOSE
SGETRI computes the inverse of a matrix using the LU factorization
computed by SGETRF.
This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).
ARGUMENTS
 N (input) INTEGER

The order of the matrix A. N >= 0.
 A (input/output) REAL array, dimension (LDA,N)

On entry, the factors L and U from the factorization
A = P*L*U as computed by SGETRF.
On exit, if INFO = 0, the inverse of the original matrix A.
 LDA (input) INTEGER

The leading dimension of the array A. LDA >= max(1,N).
 IPIV (input) INTEGER array, dimension (N)

The pivot indices from SGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).
 WORK (workspace/output) REAL array, dimension (MAX(1,LWORK))

On exit, if INFO=0, then WORK(1) returns the optimal LWORK.
 LWORK (input) INTEGER

The dimension of the array WORK. LWORK >= max(1,N).
For optimal performance LWORK >= N*NB, where NB is
the optimal blocksize returned by ILAENV.
If LWORK = 1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, U(i,i) is exactly zero; the matrix is
singular and its inverse could not be computed.
Pages related to sgetri
 sgetri (3)
 sgetrf (l)  computes an LU factorization of a general MbyN matrix A using partial pivoting with row interchanges
 sgetrs (l)  solves a system of linear equations A * X = B or Aaq * X = B with a general NbyN matrix A using the LU factorization computed by SGETRF
 sgetc2 (l)  computes an LU factorization with complete pivoting of the nbyn matrix A
 sgetf2 (l)  computes an LU factorization of a general mbyn matrix A using partial pivoting with row interchanges
 sgebak (l)  forms the right or left eigenvectors of a real general matrix by backward transformation on the computed eigenvectors of the balanced matrix output by SGEBAL
 sgebal (l)  balances a general real matrix A
 sgebd2 (l)  reduces a real general m by n matrix A to upper or lower bidiagonal form B by an orthogonal transformation